1. Field of the Invention.
The present invention relates generally to cutting tools, and in particular to a tool and method for separating a vehicle glazing seam.
2. Description of the Prior Art.
Fixed vehicle glazing, especially automobile windshields and rear windows, is typically secured in place with bonding or gasket material forming a bead or seam between the glazing and the vehicle body. Exemplary bonding materials include rubber, urethane, epoxy, silicone, etc. The bonding material generally forms a seam between a perimeter of the glazing and a frame (sometimes referred to as a "fence") defined by the vehicle body.
Glazing sometimes has to be removed for replacement, salvage or resealing. It may be acceptable to destroy damaged glazing in the process of removing it for replacement, but for salvage and resealing operations the glazing must be removed intact and undamaged. Removal of glazing generally requires separation of its bonding material seam.
A variety of devices and methods have heretofore been proposed for separating vehicle glazing seams. For example, the Barber U.S. Pat. No. 4,080,734 discloses a method and percussion tool for removing a vehicle windshield. The tool includes wing portions with blades projecting therefrom to define L-shaped cutting edges for separating a bonding material seam. A pneumatic tool holder or a hammer provides blows for advancing the Barber tool, but the blows can damage the glazing. Seam cutting devices driven by reciprocating power tools are disclosed in the Edwards U.S. Pat. No. 3,924,327 and the Lock U.S. Pat. No. 4,395,825.
It has also been proposed to mount blades specially designed for separating bonding material on oscillating power tools. For examples, see the Morford et al. U.S. Pat. No. 4,215,475 and the Grunikiewicz et al. U.S. Pat. No. 4,543,720. The Morford et al. tool includes a handle mounted on a cable for pulling the tool around the perimeter of a glazing pane to be removed.
Other prior art devices include heated blades, or "hot knives", for melting the bonding material of the glazing seam. Such tools are available from the Pittsburg Plate Glass Company (PPG) in Pittsburg, Pa. under the trademark SWIV-L-CUT. Although a cutting tool hot enough to melt the bonding material can facilitate removal of the glazing pane, damage to the vehicle can result from scorching. Also, the different melting temperatures of various bonding materials tend to limit the usefulness of particular hot knives to only the bonding materials that they were designed for.
Yet another technique for removing glazing panels involves stringing a thin wire through the bonding material seam and pulling it around the perimeter of the glazing. This procedure generally requires two workers to guide and pull the wire, one on the inside of the vehicle and the other on the outside.
The prior art tools and methods for separating glazing seams tended to be cumbersome, tedious, labor intensive and limited in their application to relatively few bonding materials. Furthermore, many of the prior art cutting tools and methods were destructive of the glazing. Heretofore there has not been available a cutting tool and method with the advantages and features of the present invention.